本题用分步积分法可以解. ∫ln(1+x^2)dx =x*ln(1+x^2)-∫x*d(ln(1+x^2)) =x*ln(1+x^2)-∫2*x^2/(1+x^2)dx =x*ln(1+x^2)-2*∫[1-1/(1+x^2)]dx =x*ln(1+x^2)-2*x+2∫1/(1+x^2)dx =x*ln(1+x^2)-2*x+2*arctanx+c...